Re: your mail

} } In article <1eit8cINN5ta@emory.mathcs.emory.edu> you write: } >> } >> In the good old days of SE, a table with a high level of activity } >> (i.e. deletions/inserts) became riddled with old data row slots } >> which were available for re-write, and the index began to look like } >> swiss cheese. To correct this periodic unload/loads or cluster } >> manipulation or ALTER TABLE (same as an unload/load but more user-friendly) } >> were needed to keep index and data table efficiency at peak. } >> } >> Is this also true of Online? Or does Online do this automagically? } >> } >Raw Online space does get very fragmented, especially if you are short } >of room in the partition. Table extents become very small and numerous } >and it causes performance problems. Tables can generally have about } >240 extents, and it is possible to reach that value and come to a grinding } >halt. } } Whoa! Informix STRONGLY recommends that you try to keep the number of } extents at 8 or below to keep performance up. I personally have seen } performance begin to fall off when a table reaches more than 10 extents. } Also, there is a limit to the number of extents per table (it is hard- } ware and OS dependent -- for a Sun 4/470 running SunOS 4.1.1 and Online } 4.1 the limit is 213) and if this is exceeded CORRUPTION will result. } > I agree *wholeheartedly*, and always try to keep my extents to a minimum. I'm interested in your statement about corruption. When we accidently exceeded the number of extents, I got errors returned, but I have not seen corruption. What have you experienced? } >We regularly monitor all our production systems extents and partition } >fragmention. Tbunloading and tbloading the database back typically puts } >all the data for each table in the first extent (if there is enough } >contiguous room). We then carefully set all the next extents on the } >tables, to accomodate future growth. If tbunloading is unreasonable } >because of the database size, we will create an empty new table, with } >the first extent set, and copy the data from the old table to the } >new table. } >-- -- Naomi Walker (aka N7FSA) naomi%anasaz.UUCP@asuvax.eas.asu.edu Enthusiasm is caught, In tennis, not taught. love means nothing.